West Side Sanitary Sewer

Challenge

Collection system planning is a cost-effective way to assess and maintain a city’s current system, and aids in positioning the city for economic growth. More importantly, it protects its citizens from flooded streets, basement backups, and the costs associated with such problems. FOX Engineering was selected to design a new wastewater treatment facility to replace the aged and overloaded plant. Prior to starting the design, FOX worked with the city to prepare an amendment to the city’s sanitary sewer facility plan. The city was required by the Iowa DNR to address inflow and infiltration(I/I) in the sanitary sewer system and eliminate bypassing at the Sunset Park pump station.

Solution

Several options were considered, including replacing the pump station with a new, larger capacity pump station, and eliminating the pump station by constructing a new gravity sanitary sewer. Due to time constraints required as part of the administrative order, FOX recommended replacing the Sunrise Park lift station with an interceptor sewer to the new wastewater treatment facility site. This was the most cost-effective, lowest-maintenance, and most sustainable long-term solution. City operators and staff agreed that eliminating the pumping station was the best solution and authorized FOX to proceed with design and easement acquisition.

FOX also modeled the proposed interceptor sewer and other new sewers to determine the effects downstream to the new wastewater treatment facility (WWTF). The analysis was used to determine if the existing plant design and equalization basin would have adequate capacity for the large increase in flows.

Outcome

The project was separated into three phases for construction. Accommodations were made for property owners to ensure crop planting was not interrupted; this saved the city from paying for crop damages. In all 3 phases the contractor met the substantial completion dates and connections were made in the 3rd (final) phase to the new interceptor after the new wastewater treatment plant was operational.

The West Side Sanitary Sewer Interceptor project was completed on schedule. Change orders totaled approximately 0.26% of the contract price of $2.8 Million.